Question

Which of the following occurs when a cell repairs a double-strand DNA break by the process of nonhomologous end joining? 1.The DNA sequence at the site of repair is altered by a short addition 2.The original DNA sequence at the site of repair is reconstituted with 100% accuracy. 3.The DNA sequence at the site of repair is altered by a short deletion. 4The DNA sequence at the site of repair matches that of a homologous chromosome. 5The DNA sequence at the site of repair contains a short segment of telomere DNA

Answer 1

Answer:

option 3

Explanation:

In non-homologous end joining, the break ends are directly ligated together without the need for a homologous template unlike the homologous repair. this form of repair uses short homologous sequences of DNA termed microhomologies to direct repair and these microhomologies are seen as single-stranded overhangs found on the ends of double-strand breaks. When the overhangs are perfectly compatible, NHEJ ligates and repair the break. When these overhangs are not compatible, imprecise repair leading to deletion of nucleotides can also occur which is much more common .

Answer 2

Answer:

3.The DNA sequence at the site of repair is altered by a short deletion.  

Explanation:

The nonhomologous end-joining (NHEJ) is a pathway that repairs double-strand breaks in the DNA backbone. The NHEJ pathway directly ligates broken ends in the DNA strands through an enzyme complex that includes DNA protein kinases